Can anyone help with the following code snippet?  It's intended to update 
an Access 2000 database using DataList?  The error is in the 
line "objInitialsParam.Value = txtInitials.Text" and the error message 
is : Exception Details: System.NullReferenceException: Object reference 
not set to an instance of an object.



Sub dlstRMChecks_UpdateCommand( s As Object, e As 
DataListCommandEventArgs ) 
	Dim Conn As OleDbConnection
	Dim strUpdate As String
	Dim cmdUpdate as OleDbCommand
	Dim strForm As String
	Dim txtInitials As TextBox
	Dim txtTo As TextBox
	Dim txtForm As TextBox
	Dim strInitials as String
	Dim strTo as String
	
	Dim objInitialsParam as OleDbParameter
	Dim objToParam as OleDbParameter
	Dim objFormParam as OleDbParameter
	
	strForm = dlstRMChecks.DataKeys( e.Item.ItemIndex )
	
	 
	 'HERE I OPEN THE CONNECTION, WHICH IS NOT THE PROBLEM
	strUpdate = "Update RMChecks Set Initials= @Initials, To = @To 
Where Form=@Form"
	
	cmdUpdate = New OleDbCommand( strUpdate, Conn )
	
	objInitialsParam = cmdUpdate.Parameters.Add( "@Initials", 
OleDbType.Char )
	objInitialsParam.Direction = ParameterDirection.Input
	objInitialsParam.Value = txtInitials.Text
	
	objToParam = cmdUpdate.Parameters.Add( "@To", OleDbType.Char )
	objToParam.Direction = ParameterDirection.Input
	objToParam.Value = txtTo.Text
	
	objFormParam = cmdUpdate.Parameters.Add ("@Form", OleDbType.Char )
	objFormParam.Direction = ParameterDirection.Input
	objFormParam.Value = strForm
	
	Conn.Open
	cmdUpdate.ExecuteNonQuery()
	Conn.Close()
	dlstRMChecks.EditItemIndex = -1
	BindDataList
End Sub

A portion of the UI is:

<EditItemTemplate>
		<tr>
			<td>
				<asp:TextBox
				ID="txtInitials"
				Text='<%# Container.DataItem( "Initials" ) 
%>'
				Runat="Server" />
			</td>
			<td>
				<asp:TextBox
				ID="txtTo"
				Text='<%# Container.DataItem( "To" ) %>'
				Runat="Server" />
			</td>
			<td>
				<asp:TextBox
				ID="txtForm"
				Text='<%# Container.DataItem( "Form" ) %>'
				Runat="Server" />
			</td>
		</tr>

Thanks for any help.

Steve

Hi Steve

Is the VB.NET code in a separate file from the ASP.NET stuff (e.g. using the
codebehind= or src= attribute in the ASPX file's Page directive)? If so, I
think that any objects that you want to use in both the code and the ASP.NET
need to be declared as:

Protected WithEvents txtTo As TextBox

The code-behind is a different .NET class from the ASPX. The ASP.NET
interpreter converts the ASPX into a .NET class that inherits from the
code-behind class. If you want to use variables in both classes then they
must be declared as Protected in the base class. Otherwise .NET thinks of
them as two different variables.

I'm not 100% sure about this solution though ... I'd be interested to know
if it works. :)

Regards

David Barnes
Wrox Editor

-- 
So You'd Like to Program ASP.NET Websites?
http://www.amazon.com/exec/obidos/tg/guides/guide-display/-/YAEJ7I55O1ED/104
-0520375-7947930

> -----Original Message-----
> From: steveproctor@c... [mailto:steveproctor@c...]
> Sent: 16 June 2002 19:42
> To: aspx_beginners
> Subject: [aspx_beginners] Updating Access 2000 Database with 
> ASP.NET and
> DataList
> 
> 
> Can anyone help with the following code snippet?  It's 
> intended to update 
> an Access 2000 database using DataList?  The error is in the 
> line "objInitialsParam.Value = txtInitials.Text" and the 
> error message 
> is : Exception Details: System.NullReferenceException: Object 
> reference 
> not set to an instance of an object.
> 
> 
> 
> Sub dlstRMChecks_UpdateCommand( s As Object, e As 
> DataListCommandEventArgs ) 
> 	Dim Conn As OleDbConnection
> 	Dim strUpdate As String
> 	Dim cmdUpdate as OleDbCommand
> 	Dim strForm As String
> 	Dim txtInitials As TextBox
> 	Dim txtTo As TextBox
> 	Dim txtForm As TextBox
> 	Dim strInitials as String
> 	Dim strTo as String
> 	
> 	Dim objInitialsParam as OleDbParameter
> 	Dim objToParam as OleDbParameter
> 	Dim objFormParam as OleDbParameter
> 	
> 	strForm = dlstRMChecks.DataKeys( e.Item.ItemIndex )
> 	
> 	 
> 	 'HERE I OPEN THE CONNECTION, WHICH IS NOT THE PROBLEM
> 	strUpdate = "Update RMChecks Set Initials= @Initials, To = @To 
> Where Form=@Form"
> 	
> 	cmdUpdate = New OleDbCommand( strUpdate, Conn )
> 	
> 	objInitialsParam = cmdUpdate.Parameters.Add( "@Initials", 
> OleDbType.Char )
> 	objInitialsParam.Direction = ParameterDirection.Input
> 	objInitialsParam.Value = txtInitials.Text
> 	
> 	objToParam = cmdUpdate.Parameters.Add( "@To", OleDbType.Char )
> 	objToParam.Direction = ParameterDirection.Input
> 	objToParam.Value = txtTo.Text
> 	
> 	objFormParam = cmdUpdate.Parameters.Add ("@Form", 
> OleDbType.Char )
> 	objFormParam.Direction = ParameterDirection.Input
> 	objFormParam.Value = strForm
> 	
> 	Conn.Open
> 	cmdUpdate.ExecuteNonQuery()
> 	Conn.Close()
> 	dlstRMChecks.EditItemIndex = -1
> 	BindDataList
> End Sub
> 
> A portion of the UI is:
> 
> <EditItemTemplate>
> 		<tr>
> 			<td>
> 				<asp:TextBox
> 				ID="txtInitials"
> 				Text='<%# Container.DataItem( 
> "Initials" ) 
> %>'
> 				Runat="Server" />
> 			</td>
> 			<td>
> 				<asp:TextBox
> 				ID="txtTo"
> 				Text='<%# Container.DataItem( "To" ) %>'
> 				Runat="Server" />
> 			</td>
> 			<td>
> 				<asp:TextBox
> 				ID="txtForm"
> 				Text='<%# Container.DataItem( 
> "Form" ) %>'
> 				Runat="Server" />
> 			</td>
> 		</tr>
> 
> Thanks for any help.
> 
> Steve
> 

David,

Thanks for the reply.  But I'm not using any code behind for this 
application, so I don't think that's the problem.

Steve

> Can anyone help with the following code snippet?  It's intended to 
update 
a> n Access 2000 database using DataList?  The error is in the 
l> ine "objInitialsParam.Value = txtInitials.Text" and the error message 
i> s : Exception Details: System.NullReferenceException: Object reference 
n> ot set to an instance of an object.

> 

> Sub dlstRMChecks_UpdateCommand( s As Object, e As 
D> ataListCommandEventArgs ) 
	> Dim Conn As OleDbConnection
	> Dim strUpdate As String
	> Dim cmdUpdate as OleDbCommand
	> Dim strForm As String
	> Dim txtInitials As TextBox
	> Dim txtTo As TextBox
	> Dim txtForm As TextBox
	> Dim strInitials as String
	> Dim strTo as String
	> 
	> Dim objInitialsParam as OleDbParameter
	> Dim objToParam as OleDbParameter
	> Dim objFormParam as OleDbParameter
	> 
	> strForm = dlstRMChecks.DataKeys( e.Item.ItemIndex )
	> 
	>  
	>  'HERE I OPEN THE CONNECTION, WHICH IS NOT THE PROBLEM
	> strUpdate = "Update RMChecks Set Initials= @Initials, To = @To 
W> here Form=@Form"
	> 
	> cmdUpdate = New OleDbCommand( strUpdate, Conn )
	> 
	> objInitialsParam = cmdUpdate.Parameters.Add( "@Initials", 
O> leDbType.Char )
	> objInitialsParam.Direction = ParameterDirection.Input
	> objInitialsParam.Value = txtInitials.Text
	> 
	> objToParam = cmdUpdate.Parameters.Add( "@To", OleDbType.Char )
	> objToParam.Direction = ParameterDirection.Input
	> objToParam.Value = txtTo.Text
	> 
	> objFormParam = cmdUpdate.Parameters.Add ("@Form", 
OleDbType.Char )
	> objFormParam.Direction = ParameterDirection.Input
	> objFormParam.Value = strForm
	> 
	> Conn.Open
	> cmdUpdate.ExecuteNonQuery()
	> Conn.Close()
	> dlstRMChecks.EditItemIndex = -1
	> BindDataList
E> nd Sub

> A portion of the UI is:

> <EditItemTemplate>
	> 	<tr>
	> 		<td>
	> 			<asp:TextBox
	> 			ID="txtInitials"
	> 			Text='<%# Container.DataItem( "Initials" ) 
%> >'
	> 			Runat="Server" />
	> 		</td>
	> 		<td>
	> 			<asp:TextBox
	> 			ID="txtTo"
	> 			Text='<%# Container.DataItem( "To" ) %>'
	> 			Runat="Server" />
	> 		</td>
	> 		<td>
	> 			<asp:TextBox
	> 			ID="txtForm"
	> 			Text='<%# Container.DataItem( "Form" ) %>'
	> 			Runat="Server" />
	> 		</td>
	> 	</tr>

> Thanks for any help.

> Steve

here is a debugging suggestion that i use to find where i might have gone
wrong. what i would do is build the SQL statment from scratch and then
assign it to a string variable. then create a label on your form. create
your connections to your DB and then implement the 'bind' of data within a
'try..catch' statment. include inside the 'try..catch' statement the new
label. with in the 'try' portion of the statement pass a string to label
acknowledgment that the process is going correctly. on the flip side, with
in the 'catch' portion of the statement, pump in the SQL statment that you
wrote. i find this helpfull because nine times out of ten the connection to
the db is correct but there is something wrong with my SQL statement. this
way you can see for the most part that you are doing stuff correct. i know
that there is nothing more iritating than not being able to see what is
wrong with your code.
----- Original Message -----
From: <steveproctor@c...>
To: "aspx_beginners" <aspx_beginners@p...>
Sent: Sunday, June 23, 2002 1:32 PM
Subject: [aspx_beginners] Re: Updating Access 2000 Database with ASP.NET and
DataList


> David,
>
> Thanks for the reply.  But I'm not using any code behind for this
> application, so I don't think that's the problem.
>
> Steve
>
> > Can anyone help with the following code snippet?  It's intended to
> update
> a> n Access 2000 database using DataList?  The error is in the
> l> ine "objInitialsParam.Value = txtInitials.Text" and the error message
> i> s : Exception Details: System.NullReferenceException: Object reference
> n> ot set to an instance of an object.
>
> >
>
> > Sub dlstRMChecks_UpdateCommand( s As Object, e As
> D> ataListCommandEventArgs )
> > Dim Conn As OleDbConnection
> > Dim strUpdate As String
> > Dim cmdUpdate as OleDbCommand
> > Dim strForm As String
> > Dim txtInitials As TextBox
> > Dim txtTo As TextBox
> > Dim txtForm As TextBox
> > Dim strInitials as String
> > Dim strTo as String
> >
> > Dim objInitialsParam as OleDbParameter
> > Dim objToParam as OleDbParameter
> > Dim objFormParam as OleDbParameter
> >
> > strForm = dlstRMChecks.DataKeys( e.Item.ItemIndex )
> >
> >
> >  'HERE I OPEN THE CONNECTION, WHICH IS NOT THE PROBLEM
> > strUpdate = "Update RMChecks Set Initials= @Initials, To = @To
> W> here Form=@Form"
> >
> > cmdUpdate = New OleDbCommand( strUpdate, Conn )
> >
> > objInitialsParam = cmdUpdate.Parameters.Add( "@Initials",
> O> leDbType.Char )
> > objInitialsParam.Direction = ParameterDirection.Input
> > objInitialsParam.Value = txtInitials.Text
> >
> > objToParam = cmdUpdate.Parameters.Add( "@To", OleDbType.Char )
> > objToParam.Direction = ParameterDirection.Input
> > objToParam.Value = txtTo.Text
> >
> > objFormParam = cmdUpdate.Parameters.Add ("@Form",
> OleDbType.Char )
> > objFormParam.Direction = ParameterDirection.Input
> > objFormParam.Value = strForm
> >
> > Conn.Open
> > cmdUpdate.ExecuteNonQuery()
> > Conn.Close()
> > dlstRMChecks.EditItemIndex = -1
> > BindDataList
> E> nd Sub
>
> > A portion of the UI is:
>
> > <EditItemTemplate>
> > <tr>
> > <td>
> > <asp:TextBox
> > ID="txtInitials"
> > Text='<%# Container.DataItem( "Initials" )
> %> >'
> > Runat="Server" />
> > </td>
> > <td>
> > <asp:TextBox
> > ID="txtTo"
> > Text='<%# Container.DataItem( "To" ) %>'
> > Runat="Server" />
> > </td>
> > <td>
> > <asp:TextBox
> > ID="txtForm"
> > Text='<%# Container.DataItem( "Form" ) %>'
> > Runat="Server" />
> > </td>
> > </tr>
>
> > Thanks for any help.
>
> > Steve
>